This invention relates generally to improved expanders for expanding tubes in boilers or the like. More particularly, but not by way of limitation, this invention relates to an improved expander for expanding and simultaneously flaring the ends of tubes in boilers or the like.
In the past, considerable difficulty has been encountered in the construction of boilers because of the difficulty of both expanding tubes in the tube sheets and flaring the ends of the tube projecting from the tube sheets to the desired angle. With the type of expanders previously used, placing the expander too deeply into the tubes could result in the inadequate expansion of the tube to form the proper seal. Also, if the expander is set too deep in the tube, the flare may be bent outwardly so that the tube is actually cut off at the face of the tube sheet. If the expander is not placed deeply enough in the tube, the tube may be expanded before the flare rolls are sufficiently engaged to expand the flare to the required degree.
Most often, when expanding and flaring boiler tubes, a torque control device is used that senses the torque applied and automatically shuts the rolling motor off to prevent excess tube expansion and to be sure that all tubes are virtually identical. Improper positioning of the expander relative to the tube ends can cause false indications of torque and, thus, inconsistent expansion.
An object of this invention is to provide an expander wherein the proper depth of insertion of the expander into the tubing is controlled, and thus the expander will consistently and effectively roll and expand the tube to form a seal with the tube sheet while at the same time, forming the required flare on the end of the tube.